Advanced fibre composite materials

flon) which enables PTFE to be shaped by conventional metal forming techniques, soldered and bonded with adhesives. These properties are rendered to the sheet by incorporating a copper mesh backing. (69/4/2)

BUCKNELL, C. B. Current research on the structure and mechanical properties of rubbermodified thermoplastics

Journal of Materials, 5, No 1, p 214 {March 1969) The effect of the composite structure, in terms of the glossy polymer content of rubber particles used in many rubber filled thermoplastics, on particle and composite properties are examined. Particular reference is made to stress concentrations, around the rubber particle, which lead to craze formation in glossy polymer matrices. Current research on the role of crazing in creep and fracture is discussed and areas requiring future study are indicated. (69/4/3)

DESCRIPTIVE NEWS ITEM

Modern Plastics, 46, No 6, p 63 (June 1969[ Newman Industries Incorporated of Fairhope, Alabama are manufacturing conveyor rollers from extruded, glassfilled, high-density polyethylene profiles to which the two ends are simultaneously spin-welded. The glass content varies from 3 - 4 0 % depending on roller size and the cost of the rollers is in general slightly higher than the steel equivalents. Four important performance advantages are claimed over steel, namely: non-stick properties , corrosion resistance, lighter weight and improved concentricity. A 40% increase in the total (US) market for RTP's is forecast from this application. (69/4•4)

whiskers or ductile copper wires. In the case of the copper wire/resin composites the failure strain was less than that of either the fibre or matrix individually. An explanation is given in terms of the severe local deformation of the wires in the vicinity of a matrix crack. Partially plastic failure of alumina whisker/resin composites is attributed to the discontinuous nature of the fibres and pull out of fibres during failure. (69/4/5)

HARRIS, B., BEAUMONT, P. W. R. and ROSEN, A. Silane coupling in carbon reinforced polyester resin

fibre-

Journal of Materials Science, 5, No 5, p 432 (May 1969) RAE Type 1 fibre was subjected to various surface oxidation treatments in an attempt to produce favourable conditions for chemical 'bridging' between fibre and polyester resin by the use of organosilane coatings. Oxidation of the fibres in an aqueous environment (boiling in 70% HNO3) prior to coating puts hydroxyl groups on the surface and promotes such bridging. Results of tensile and interlaminar shear properties of composites made from fibres coated with a variety of silanes a're presented, together with stereoscan studies of the fracture surfaces. (69/4/6)

MORLEY, J. G. Advanced fibre composite materials

Fibre Science and Technology, 1, No 3, p 209 {January 1969} The properties, especially fracture toughness, and potential importance of fibre reinforced materials are briefly reviewed. Particular attention is given to work carried out at Rolls Royce Limited. Modes of failure and necessary characteristics of the matrix and fibres are discussed. (69/4/7)

GRENNIER, P. and COOPER, G. A. Some observations on the fracture o f composites with a brittle matrix

Fibre Science and Technology, 1, No 3, p 219 (January 1969) A scanning electron microscope has been used to examine the fracture surfaces of specimens of an e p o x y resin reinforced with brittle alumina

SCHULTE, E. L. Improved autoclave method gives lowvoid RP parts

Modern Plastics, 46, No 5, p 112 (May 1969) A 'no-bleed' method of composite layup is described for boron fibre/epoxy

composite manufacture by an auto clave processing technique. No resin is allowed to flow from the mould during autoclaving so that the required fibre volume and spacing can be achieved with a high degree of accuracy. Composite void content is minimal since all the autoclave pressure is taken up in forcing the fluid resin into the interstitial positions in the fibre lay-up. Low-void composites were also produced from graphite filaments in e p o x y by this method. An attractive advantage of the nobl.eed method is, that in addition to resin economy, it can accommodate fairly large variations in resin flow and gelation characteristics. (69/4•8)

SMITH, T. R. and OWEN, M. J. Progressive nature of fatigue damage in RP

Modern Plastics 46, No 5, p 128 {May 1969) Change in modulus is used to detect the progress of internal damage in glass-reinforced plastics through the two intermediate stages of debonding and resin-cracking to ultimate failure. For six laminates tested a linear relationship between initial modulus and stress at the onset of debonding was established and debonding was found to occur at a nominal strain of 0.3%. S - N curves presented for four types of laminate show the important parameters to be maximum strain and mean stress in the cycle. In the light of results presented, the authors question the validity of existing design criteria for GRP and suggest that strain at debonding might prove a useful quality control test. (69/4/9)

Structures GRANT, R. M. and BROWN, G. M. Holographic (HNDT)

non-destructive

testing

Materials evaluation, 27, No 4, p79 (April 1969) Tyres, sandwich structures, disc brakes, honeycombes etc can now be quickly tested by a holographic interferometry method. A pair of similar but slightly different holograms of the object before and after deformation are superimposed so as to create

COMPOSITES September 1969 63